Anti-cavitation structure for sink drains and the like



y 1966 w. G. MASON ETAL 3,251,303

ANTICAVITATION STRUCTURE FOR SINK DRAINS AND THE LIKE Filed Sept. 15, 1963 INV TORS 5424270? 'L/ /%0A/ %//z4/4/v W450/1/ United States Patent Mich.

' Filed Sept. 13, 1963, Ser. No. 308,715

7 Claims. (Cl. 10325) The present invention relates to an anti-cavitation structure for sink drains and the like and more particularly to a unique chamber structure locatable between tank, sink, or tray and the emptying pump. In addition to avoiding cavitation in interference with pump operation, the device of the present invention includes pump control means so that stopping of the pump occurs inelimination of pump damage caused by either allowing the pump to run dry or prematurely admitting a mixture of air and water to the pump.

Characteristics of a particular pump affect the cavitation condition occurring at the impeller, for example in centrifugal pumps. While cavitation generally may in clude vaporization in the stream which occurs when the absolute pressure becomes equal to the vapor pressure of the fluid, thereby causing vapor pockets, cavitation in the sense of the present invention has reference to the broader phenomena wherein vapor or air or gas forms pockets which disturb the flow through the pump impeller and by their collapse produce vibration, noise and serious destruction of impeller and case. 7

In many homes and industrial applications the drain or sewer line is frequently above the level of sinks, or

reservoirs so that when such sinks or reservoirs are to be emptied, pump means must ultimately be applied to lift liquid such as waste water above the outside drain level. for this purpose centrifugal pumps are usually employed in a local drain line beneath the sink or reservoir. Characteristic of these situations are domestic laundry tray installations and considerable effort has been made as by pressure sensitive means, floats, and the like, to time or terminate the working of the pump so as to avoid the intrusion of air and gases while the pump is operating. If the pump controls are adequate enough to shut off the pump, a considerable volume of unpumped liquid is retained in the tray or sink. If the controls are more finely adjusted to allow complete draining, then air is sucked into the eye of the impeller and serious damage can and ultimately does occur.

Known work in the patent art bearing on this structure includes our U.S. Letters Patent 2,945,446 and the US. Letters Patent 2,840,000, 2,222,595 and 2,011,626.

It is accordingly the principal object of the present invention to remove the development of an environment wherein air is included in the flow to the pump and providing an auxiliary vented reservoir beneath the sink, tank or reservoir served by the pump so as to avoid the damage to the pump which occurs as the pump operates dry.

Another object is to integrate a pressure sensitive pump control in the vented reservoir structure and avoiding the inclusion of air from the sink so that the auxiliary reservoir provides an accurate monitor of pump shut-off.

Still another object is to provide a vented chamber structure which is simple to install in any drain line and which is simple to fabricate and employs substantially no moving parts.

Still another object is to provide a vented chamber structure which is coupled in-line with flow from traysink or reservoir to pump and which is not easily fouled or contaminated by flow included debris.

Other objects; including economy, ease of installation and compactness will be appreciated as the description proceeds.

In the drawing:

FIGURE 1 is a schematic line drawing elevation view of a structure in accord with the present invention and indicating the off or rest condition.

FIGURE 2 is a schematic elevation view as in FIGURE 1 and indicating the condition when liquid level in the reservoir has closed the pump monitor switch so that the pump is operable.

FIGURE 3 is a schematic elevation view as in FIGURE 1 and FIGURE 2 indicating that the pump is operating and that the reservoir or sink is approaching empty and a characteristic whirlpool has developed extending beneath the drain of the tray or sink and indicating pressure relief occurring through the breather opening to equalize ambient pressure with internal chamber pressure.

FIGURE 4 is a schematic elevation view as in FIG- URES 1, 2 and 3 and including smooth drainage from the auxiliary reservoir in avoidance of included air.

FIGURE 5 is a schematic elevation view as in FIG- URES 1, 2, 3 and 4 and indicating the moment of shut off of the pump by reason of the pressure sensitive switch being relieved of pressure from inside the auxiliary reservoir or chamber. FIGURE 6 is a side elevation view of a chamber structure in accord with the present invention and indicating the attached pressure sensitive switch, the pressure relief connection, and the simple line couplings.

FIGURE 7 is a partial cross section taken through the chamber or auxiliary or reservoir of the present invention along the line VII-VII of FIGURE 8 and indicating pump attachment.

FIGURE 8 is a top plan view of the structure as seen in FIGURE 6.

GENERAL DESCRIPTION In general, the present invention comprises a pressure relieved enclosure or chamber through which vertical delivery conduit is passed and wherein the conduit is gapped near the top of the chamberand the conduit is provided with at least one radial drain opening at or near the bottom of the chamber. The chamber is accordingly positioned about the conduit so that the conduit is in a communicating relation with the chamber at top and bottom. A relief opening is provided through the chamber wall at or above the elevation of the gap in the conduit and an opening for a pressure sensitive switch is provided radially through the chamber or auxiliary reservoir on an elevation substantially the same as the radial drain opening through the conduit. The conduit thus passes axially through the chamber and is provided with conplings for in-line attachment to a drain line between sink or reservoir served and the pump. While generally the chamber is defined by a pair of shell pieces connected in a plane transverse to the axis of the conduit, it will also be appreciated that such shells could be longitudinally joined in a plane passing through the axis of the conduit and tightly secured to the conduit at the ends thereof.

The relief opening must provide relief of the chamber to the atmosphere and this is preferred to be accomplished by a stand tube or pipe which extends above the working level of fluid to be placed in the principal reservoir. This can, of course, be accomplished by a simple float or ball check valve at the relief opening which closes when the chamber is under positive static pressure and opens upon a negative pressure or drop of water level in the chamber or auxiliary reservoir. The vent line extending upward is preferred because less chance of fouling can occur than in reliance on a mechanical valve. A polyethylene tube, for example, has proved very satisfactory and rub- Patented May 17, 1966 3 her, vinyl, and metal can be equally advantageously employed in a foolproof manner.

The chamber described need not be large and its size may be varied with adaptation to particular volumes and pumps used. The chamber may also be variously shaped and positioned in respect to the conduit so long as the recited communication between chamber and conduit is maintained. Actuation of the pump is usually by a manual switch which cannot energize the pump unless the condition on the pressure sensitive switch indicates an adequate amount of liquid to close the switch. When the pump is energized, the chamber is substantially filled with liquid and this remains true until the whirlpool breaks into the gap between the conduit through the chamber. Then the vacuum causing the whirlpool breaks, by reason of the pressure equalizing action, and water or liquid is thereupon drained smoothly from the conduit and from the reservoir without allowing cavitation to intrude on the pump operation and the auxiliary reservoir and chamber assures wetting of the impeller of the pump while the pump is energized. The pressure sensitive switch shuts off the electrical circuit to the pump when the water level in the chamber drops to the level of the switch so that the pump cannot be accidentally started until the pressure sensitive switch again closes as a consequence of liquid pressure.

SPECIFIC DESCRIPTION By reference to the drawing and more particularly to FIGURES 1-5 the environmental setting of the present invention will be best appreciated and its operational sequencing will be understood. The unique chamber 11, concentric about the conduit 12 and with vent or pressure relief line 13 extending above the highest working level of sink 14, is shown located in the drain 15 between sink 14 and pump 16. The pressure sensitive monitoring switch 17 extends from the chamber 11. An upper gap 18 is provided in the conduit 12 and a drain opening 19 is provided radially through the wall of the conduit 12 near the bottom of the chamber 11. It will be appreciated that the gap 18 may be formed by plural radial openings through the conduit 12 or, as shown, the conduit 12 may be actually broken and spaced apart as shown on the common conduit axis, the gap 18 then being in a plane at right angles to the axis of conduit 12. The gap 18 is located at substantially the same elevation as the vent opening 20 to which the vent tube 13 is communicatingly atached. In FIGURE 1, the structure is at rest and the pump monitor switch 17 is in the cit position. While in this position manual separate electrical control over the pump is inoperative, the switch 17 exercising a master control over the pump motor 21. In FIGURE 2 the chamber 11 and sink 14 have been filled to operating level as by water 22 and accondingly the vent tube 13 is filled to substantially the same level. The pump circuit (not shown) is thus armed by reason of the fact that switch 17 is closed by the static pressure on the switch 17 and in this position the pump 16 may be energized. In FIGURE 2 this has occurred and the pump 16 is receiving water at the eye of the impeller 23 and is pumping the water 22 from the system via the pipe 24 as to sewer or other disposal. As will be appreciated as the water level drops in the sink 14, the water level correspondingly drops in the vent tube 13. While water remains in the vent tube 13 the chamber 11 remains filled and under static positive pressure.

As the sink 14 approaches emptying as seen in FIGURE 3 a characteristic swirling or whirlpool action occurs in which an air column extends through drain 15 and into the conduit 12. The air is separated at the gap 18 and the vent 13 equalizes the pressure in the chamber 11 and breaks the column of air thus eliminating cavitation to the pump 16 and impeller 23.

Collaterally, the gap 18 allows a fraction of the water 22 to replenish the supply in the chamber 11 at a rate mon axis through the chamber 25.

approximating the escape through radial opening 19 in the conduit 12. In FIGURE 4 final draining occurs as the chamber 11 empties into conduit 12 through radial opening 19 allowing smooth pump down of the water 22 free of included air with immersion of the impeller 23. The draining of the auxiliary reservoir or chamber 11 proceeds until the static pressure on the switch 17 is relieved as best shown in FIGURE 5. This shuts off the motor 21 and inertial action of the pump 16 substantially empties the drain 15 and the condition seen in FIGURE 1 reobtains.

The function of the vent 13 acting through the opening and in cooperation with the gap 18 is merely to break the vacuum conditions within the chamber 11 and accordingly eliminate the major source of cavitation. Accordingly, a simple check valve such as a floating ball or the like well known in the art may be employed in avoidance of the vent line 13. However, experience has dictated the illustrated vent-line as being substantially trouble-free where valves employed tend to clog and unseat from lint and debris carried by the liquid pumped.

In FIGURES 6, 7 and 8 a precise preferred embodiment of the invention is described. As will be seen a chamber 25 (FIGURE 7) is defined by two substantially hemispheric shells 26 and 27 secured together by facing flanges 23 and 29 in water tight and airtight sealed relation as by gasket 30 and fasteners 31. In the embodiment shown the shells 26 and 27 are joined in a horizontal plane, but it is intended that such shells might also be joined in a vertical plane passed through the axis of the conduit 34 and clamped to the conduit in air and water tight manner.

An opening 32 is provided in the end of the upper shell 26 and a corresponding opening 33 is provided in the lower shell 27, both openings 32 and 33 being on a com- A conduit 34 is passed through the openings 33 and 32 and a gap 35 is provided in the conduit 34 near the top of the chamber 25 as viewed in FIGURE 7 so that the interior of the conduit 34 is in flow communication with the chamber 25. As will be appreciated, the gap 35 may be formed by a discontinuity of the conduit 34 as shown or by suitable radial openings therethrough in the position indicated.

Proximate to the lower portion of the conduit 34 where it connects with the end of shell 27, a radial opening 36 extends through the wall of the conduit 34 also providing flow communication between the contents of chamber 25 and conduit 34. A coaxial opening 37 is provided through the wall of the lower shell 27 in substantial register with the radial opening 36. A nipple 38 is threadably inserted in the opening 36 and pressure sensitive switch 39 of the diaphragm type, for example, is operatively connected thereto. Accordingly the diaphragm element 40 is acted upon by changes in the pressure condition in the chamber 25. i

In the upper shell 26 a vent opening 41 is provided radially through the wall of the shell 26 and having its axis in substantially the same plane as the gap 35. A nipple 42 is threadably inserted in the opening 41 and a vent tube 43 is connected thereover by means of a suitable connector 44.

The conduit 34, where it passes through the openings 32 and 33 is secured fixedly to the shells 26 and 27 as by brazing, cementing or preferably by potting in-situ using, for example, a suitable potting resin such as one of the epon materials well known for excellent metal to metal bonding.

The ends of the conduit 34 extending from the shells 26 and 27 are outwardly and peripherally flanged and the flanges 45 and 46 provide sealing means to threaded drain stubs 47 and 48 as shown with gaskets 49 and 50 providing the seal in cooperation with coupling nuts 51 and 52 compressing the gaskets 49 and 50 between the stubs 47, 48 and flanges 45, 46, respectively.

- drain stubs 47 and 48. The gap 35 is variable in spacing and the opening 36 through the conduit 34 is preferred in the position shown in FIGURE 7 since it can then be drilled at the same time opening 37 is let through the wall of the lower shell 27.

Sizes of the orifices or openings may be varied considerably, but relative location in respect to each other and the chamber is considered important.

In some installations openings as gap 18 and drain 19 may be provided in an existing drain line 15 as by direct machining. In such instances, the chamber 11 is formed concentrically about the drain line 15 and opening 20 is then located at the same elevation as the gap 18 and the opening in the chamber serving the switch 17 is aligned with the drain opening 19 and the chamber is otherwise sealed as in a longitudinal gasketed flange and with suitable packing at the connection of chamber 11 to drain line 15.

In operation, the structure herein described has substantially eliminated cavitation to pumps utilized in the draining of laundry trays and the like. The use of the inventive devices has substantially extended the life of such pumps and has avoided customary noise attending the operation of such pumps. The installation is extremely simple since the chamber is attached directly in the drain between the receptacle such as a sink or laun dry tray and the pump beneath, In the preferred em bodiment no chance for leakage exists and no moving parts other than at the switch 39 are involved to wear out and require replacement. The positioning of the switch 39 is such as to facilitate occasional repair or adjustment as may be needed.

Having thus described the invention with particular reference to the preferred embodiment, it will be readily appreciated that improvements and modifications within the skill of the art can be made and such improvements and modifications are intended to be includedherein limited only by the scope of the hereinafter appended claims. I i

We claim:

1. An anti-cavitation chamber for fastening to a conduit between a liquid reservoir and a pump wherein the conduit has been provided with a radial upper gap therethrough and a lower radial drain opening, the combination comprising:

(a) a pair of flanged shells-defining, when joined, a chamber concentric about a conduit and having one upper radial opening to the atmosphere therein at an elevation corresponding to the location of an upper gap in said conduit and having a second lower radial opening therethrough at an elevation corresponding to the location of a lower radial opening through said conduit and through which flow from said chamber is recommunicated to said conduit;

(b) a vent to atmosphere in said upper radial opening and in flow communication with said chamber;

(c) a pressure sensitive switch closed when pressure within said chamber exceeds atmospheric pressure in said lower radial opening operably connected to said 7 pump; and

(d) seal means securing said chamber to said conduit above and below said opening and closing said chamber in air and water tight relation.

2. In a structure for anti-cavitation delivery of liquid from a reservoir to a pump the combination comprising: (a) a chamber defined by a pair of shell elements and closing a space about a conduit between a reservoir and a pump;

(b) a gap defined by a separation through said conduit, said gap communicating with said chamber for flow into said chamber;

(0) a vent to atmosphere opening through the wall of one of said shells near the upper portion of said one shell and at an elevation substantially the same as the elevation of said gap;

((1) a radial opening through said conduit and communicating with said chamber near the lower portion of the other of said shells for flowing contents of said chamber to said conduit; and

(e) a pressure sensitive switch through the wall of said other of said shells at about the same elevation as said radial opening whereby control over said pump is exercised.

3. An anti-cavitation structure for attachment to a drain intermediate a reservoir and a pump comprising:

(a) a conduit connectable to a drain and gapped near its upper end and provided with a radial drain opening near its lower end;

(b) a chamber defined about said conduit and communicating with said conduit through said upper gap and said opening through said conduit and closed on said conduit and having a radial opening at top at an elevation substantially the same as said gap and at bottom at an elevation substantially the same as said radial drain opening in said conduit;

(0) means communicating to atmosphere through the uppermost of said openings in said chamber and in avoidance of spillage of contents from said chamber;

(d) pressure sensitive means in the lowermost of said openings into said chamber operably connected to control said pump in accord with conditions in said chamber; and

(e) couplings on said conduit ends for securing said conduits in flow communication between a pump and a reservoir.

4. An anti-cavitation structure for sink drains and the like locatable between said sink and a pump serving said sink comprising:

(a) a conduit;

(b) a chamber defined about said conduit and in sealed relation thereto;

(c) a vent to atmosphere radially provided though the wall of said chamber;

(d) a vent tube extending upward from said vent to a selected elevation above any working liquid level and exposed to atmosphere;

(e) a radial gap in said conduit communicating with said chamber and located near the upper intersection of said conduit with said chamber .wall and at an ele vation substantially equal to the elevation of said vent whereby flow in said conduit fills said chamber;

(f) a radial drain opening through said conduit near the lower intersection of said conduit with said chamber and communicating with said chamber whereby said chamber may empty to said conduit; and

(g) pressure sensitive switch means in said chamber in control over said pump and sensing at pressure in said chamber substantially the same elevation as said radial drain.

5. In a structure for anti-cavitation delivery of liquid from a reservoir to a pump the combination comprising:

(a) a reservoir;

(b) a pump beneath said reservoir;

(c) a drain conduit intermediate said reservoir and said pump and defining an upper gap and a lower radial opening spaced apart from said gap and beneath said (d) a chamber adjacent said drain conduit and in sealed connection to said conduit whereby flow from said upper gap fills said chamber and fiow from said lower opening drains said chamber, said chamber having a pair of radial openings therethrough corresponding in elevation to said gap and said radial openings through said conduit;

(e) means in the uppermost of said radial openings through said chamber communicating to the atmosphere when pressure within said chamber is at or below atmospheric pressure; and

(f) a pressure sensitive switch in the lower of said radial openings in said chamber and in master control relation with said .pump so that said pump is operable only when said chamber contents applies pressure to said switch.

6. In a structure for anti-cavitation delivery of liquid from a reservoir to a pump the combination comprising:

(a) a reservoir;

(b) a pump beneath said reservoir;

(c) a drain conduit intermediate said reservoir and said ((1) a chamber adjacent said drain conduit and having an upper radial vent opening therethrough and a lower radial pressure sensing opening therethrough;

(e) a radial gap in said drain conduit within said chamber providing upper flow access to said chamber and at an elevation substantially the same as the elevation of said vent opening;

(f) means in said vent opening communicating atmospheric condition to said chamber when a pressure in said chamber is at or below atmospheric pressure;

(g) a lower drain opening radially through said conduit at substantially the same elevation as said lower radial pressure sensing opening for emptying said chamber to said conduit; and

(h) a pressure sensitive switch through said radial pressure sensing opening and connected to control operation of said pump in accord with pressure conditions in said chamber.

7. An anti-cavitation structure for sink drains and the like locatable between the sink and a pump serving said sink comprising:

(a) a conduit between a sink and a pump;

(b) a chamber defined around and coaxial about said conduit;

(c) a vent to atmosphere from the top of said chamber;

(d) a gap in said conduit near the top of said chamber and communicating into said chamber assuring partial flow into said chamber;

(e) a radial opening defined through said conduit near the bottom of said chamber for draining from said chamber and into said conduit; I i

(f) pressure sensitive switch means operably connected to said pump and in pressure communication with the interior of said chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,215,881 2/1917 Siemen 103-413 2,313,585 3/1943 Rupp 103-113 2,945,446 8/1960 Mason et a1 103-25 3,043,225 8/ 1962 Nielsen 103-25 FOREIGN PATENTS 165,820 8/1953 Australia.

SAMUEL LEVINE, Primary Examiner.

DONLEY J. STOCKING, Examiner.

W. L. FREEH, Assistant Examiner. 

1. AN ANTI-CAVITATION CHAMBER FOR FASTENING TO A CONDUIT BETWEEN A LIQUID RESERVOIR AND A PUMP WHEREIN THE CONDUIT HAS BEEN PROVIDED WITH A RADIAL UPPER GAP THERETHROUGH AND A LOWER RADIAL DRAIN OPENING, THE COMBINATION COMPRISING: (A) A PAIR OF FLANGED SHELLS DEFINING, WHEN JOINED, A CHAMBER CONCENTRIC ABOUT A CONDUIT AND HAVING ONE UPPER RADIAL OPENING TO THE ATMOSPHERE THEREIN AT AN ELEVATION CORRESPONDING TO THE LOCATION OF AN UPPER GAP IN SAID CONDUIT AND HAVING A SECOND LOWER RADIAL OPENING THERETHROUGH AT AN ELEVATION CORRESPONDING TO THE LOCATION OF A LOWER RADIAL OPENING THROUGH SAID CONDUIT AND THROUGH WHICH FLOW FROM SAID CHAMBER IS RECOMMUNICATED TO SAID CONDUIT; (B) A VENT TO ATMOSPHERE IN SAID UPPER RADIAL OPENING AND IN FLOW COMMUNICATION WITH SAID CHAMBER; (C) A PRESSURE SENSITIVE SWITCH CLOSED WHEN PRESSURE WITHIN SAID CHAMBER EXCEEDS ATMOSPHERIC PRESSURE IN SAID LOWER RADIAL OPENING OPERABLY CONNECTED TO SAID PUMP; AND (D) SEAL MEANS SECURING SAID CHAMBER TO SAID CONDUIT ABOVE AND BELOW SAID OPENING AND CLOSING SAID CHAMBER IN AIR AND WATER TIGHT RELATION. 